Development of Virus Resistant Watermelon Using Viral Fragments from Different Viruses

Watermelon is an important fruit crop globally. However, it is prone to several viruses that can lead to significant yield decrease. Ching-Yi Lin of National Chung Hsing University in Taiwan, together with other researchers, developed a biotech watermelon resistant to multiple virus infection. They used a single transgene with viral fragments coming from Watermelon silver mottle virus (WSMoV), Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV) and Watermelon mosaic virus (WMV) and transformed into watermelon (cultivar Feeling) through Agrobacterium-mediated transformation.

Insertion of the transgene was confirmed through Southern blot analysis. To evaluate the resistance of transgenic watermelon plants, they were exposed to CMV, CGMMV, and WMV. Two lines proved to be resistant to the individual viruses as well as to the mixture of the three viruses. These two lines were crossed and the resulting line showed resistance to CMV and WMV but not to CGMMV. Analyses revealed that the crossing of the two lines resulted to the loss of the CGMMV protein coat fragment, thus the progeny failed to exhibit resistance to CGMMV.

These findings indicate that combining various gene fragments in biotech watermelon contributed to multiple virus resistance through gene silencing. The resistance lines produced could be used in water melon breeding programs for multi-viral resistance.

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